Agglutinin responses to Salmonella pullorum in Japanese quail selected for plasma cholesterol response to adrenocorticotropin and a model describing the dynamics of the response

Methodological Considerations for Assessing Immune Defense in Reproductive Females

One of the key foci of ecoimmunology is understanding the physiological interactions between reproduction and immune defense. To assess an immune challenge, investigators typically measure an immune response at a predetermined time point that was selected to represent a peak response. These time points often are based on the immunological responses of nonreproductive males. Problematically, these peaks have been applied to studies quantifying immune responses of females during reproduction, despite the fact that nonreproductive males and reproductive females display fundamentally different patterns of energy expenditure. Previous work within pharmacological research has reported that the response to the commonly-used antigen keyhole limpet hemocyanin (KLH) varies among individuals and between females and males. In this heuristic analysis, we characterize antibody responses to KLH in females with varying reproductive demands (nonreproductive, lactating, concurrently lactating, and pregnant). Serum was taken from one animal per day per group and assessed for general and specific Immunoglobulins (Igs) G and M. We then used regression analysis to characterize the antibody response curves across groups. Our results demonstrate that the antibody response curve is asynchronous among females with varying maternal demands and temporally differs from the anticipated peak responses reflected in standardized protocols. These findings highlight the importance of multiple sampling points across treatment groups for a more integrative assessment of how reproductive demand alters antibody responses in females beyond a single measurement.

Genetic analysis of the growth curve of Rous sarcoma virus-induced tumors in chickens

White Leghorn chicks homozygous for B19 MHC haplotype were selected for 18 generations on tumor regression after inoculation in the wing web with an SR-D strain of Rous sarcoma virus (RSV) at 4 wk of age. Each chick was assigned a tumor profile index (TPI) based on age at death and size of the tumor. During 18 generations, 2,010 birds were divergently selected on TPI for either progression or regression of the tumor (P and R lines). A Brody growth curve was fitted for each bird. Brody function parameters included the asymptotic tumor volume (A), the factor for increased growth in progression phase (K1), the factor for decreased growth in regression phase (K2), age at maximum volume (Tmax), and maximum volume of the tumor (Vmax). Tumor growth curves were found to be different according to line, sex, and restriction fragment pattern Y complex Rfp-Y MHC haplotype (Yw*15, Yw*16, and Yw*17). Within the P line, birds from the Yw*16 haplotype reached Vmax at an earlier age than Yw*15 and Yw*17, but with a lower Vmax value. Within the R line, tumor growth curves of birds from Yw*16 and Yw*17 haplotypes were similar. Rank correlations between the different parameters and TPI were low (between -0.26 and 0.36). Heritability estimated by the sire component was high for Vmax (0.73). Heritabilities of Tmax and K2 were moderate (0.20 to 0.23 for Tmax and 0.18 to 0.21 for K2) allowing these traits to be used as selection criteria. Heritabilities of A and K1 were lower than 0.12. Modeling the growth curve should contribute to better distinction between progressors and regressors.

Candidate gene promoter polymorphisms and antibody response kinetics in chickens: interferon-gamma, interleukin-2, and immunoglobulin light chain

An F2 population was produced from mating G0 highly inbred (>99%) males of two MHC-congenic Fayoumi lines with G-B1 Leghorn hens. The F2 population was essentially a full-sibship with the F1 sire line reflecting MHC effect. Adult F2 hens (n = 158) were injected twice with SRBC and whole fixed Brucella abortus (BA). Agglutinating antibody titer at 7 d after primary immunization and mean titer of the final three samples (Days 18, 32, and 63 after the second immunization) were used as parameters for primary and equilibrium phases, respectively. Secondary phase parameters of minimum (Ymin), maximum titers (Ymax) and time needed to achieve minimum (Tmin) and maximum (Tmax) titers were estimated from seven postsecondary titers with a nonlinear regression model. Three candidate genes, interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and immunoglobulin G light chain (IgL) were studied. Primers for the promoter regions were designed from EMBL chicken genomic sequences. Polymorphisms between parental lines were detected by direct sequencing. Polymerase chain reaction-restriction fragment length polymorphism methods were then developed to directly detect the polymorphism. There were significant main effects (P < 0.05, general linear model analysis) of IFN-gamma polymorphism on Ymax of BA antibody and interaction of IFN-gamma by IgL on primary antibody response to SRBC and BA, and on Tmin and Ymin of antibody response to SRBC in F2 offspring of M5.1 grandsires. There were significant main effects of IFN-gamma polymorphism on Tmax of BA and interaction of IFN-gamma by IL-2 on Ymin to SRBC in F2 offspring of M15.2 grandsires. The results suggest that IFN-gamma genes play an important role in chicken primary and secondary antibody response to SRBC and BA antigens, and there exists interaction among genes for antibody production.

Genetic line and major histocompatibility complex effects on primary and secondary antibody responses to T-dependent and T-independent antigens

The effects of MHC and nonMHC (background) genetics on the kinetics of primary and secondary antibody responses to T-cell-dependent (SRBC) and T-cell-independent [Brucella abortus (BA)] antigens were investigated. Eight genetic groups were represented, with four homozygous MHC haplotypes [B1-IrGATlow (IrGAT = immune response to GAT locus); B1-IrGAThigh; B19-Ir-GATlow; B19-IrGAThigh] on two genetic backgrounds, the S1 and G lines. Birds were injected simultaneously with BA and SRBC at 4 and 7 wk of age, and blood samples were taken weekly from 4 to 10 wk of age for measurement of total agglutinating serum antibody levels. A quadratic equation and its first derivative were computed for each bird to approximate individual curve parameters: y max, the maximum titer; t max, the time required to achieve y max; and c coefficient, the rate of decline in the titer. Curve parameters of birds from different lines were analyzed separately by using the General Linear Model procedure. A second analysis that included line effect evaluated the nonMHC gene effects and their interactions with erythrocyte antigen B locus (Ea-B) or IrGAT. In the S1 line, there was an interaction (P < 0.05) between MHC haplotypes and sex for primary response to BA. In contrast, there were no significant main effects nor interactions in the G line background for primary and secondary responses to BA and SRBC. There was an effect (P < 0.05) of line background on y max for primary BA and for secondary SRBC responses. A positive correlation (P < 0.05) was found between the c coefficients of BA and SRBC secondary responses, suggesting that the rate of decline in the secondary response is similar between these T-dependent and T-independent responses. The overall results of this study indicate complex interactions between specific MHC alleles and the nonMHC background of the lines in which they are studied.

Epitopes for chicken monoclonal antibodies in spleens of selected Japanese quail lines

A line of Japanese quail selected for high plasma cholesterol is highly susceptible to diet-induced atherosclerosis. Lymphocyte epitopes recognized by mouse anti-chicken monoclonal antibodies (c-mAb), TCR-1, TCR-2, TCR-3. CD-3, CD-4, CD-8, and BU-1a/b were reacted with spleens from quail selected for high (HL) and low (LL) plasma total cholesterol and their nonselected controls (CL). Cross reactivity to c-mAb and effect of line and gender were immunohistochemically evaluated. Chicken spleens were positive controls. Quail were immunologically stimulated with either sheep red blood cells (SRBC) or Brucella abortus 2 weeks before spleens were removed. Quail spleen epitopes of all lines recognized TCR-3 and CD-8 c-mAb, but no other c-mAb. Number of reacting cells and staining intensity to the TCR-3 c-mAb were greater in the HL than in the LL regardless of the stimulating Ag or dose used. For the CD-8 c-mAb, there were no differences among lines in birds receiving SRBC. In B. abortus-immunized birds, sex x line interactions indicated that males of the HL and CL had lower responses than females but LL males were not different than females. TCR-3 and CD8 c-mAb may be useful in studying immunological mechanisms for atherosclerosis in Japanese quail.

Application of a nonlinear regression function to evaluate the kinetics of antibody response to vaccines in chicken lines divergently selected for multitrait immune response

To evaluate the kinetics of immune response to vaccines in chickens, antibody response curves were approximated to the observed antibody ratios by using a nonlinear regression function. New parameters, the curve maximum (ymax) and the time of the maximum (tmax), were calculated. The method was applied to analyze the kinetics of the serum antibody response to Mycoplasma gallisepticum (MG) and Pasteurella multocida (PM) vaccines in White Leghorn lines selected, in replicate, for 10 generations for high (High) and low (Low) multitrait immune response. Chicks were immunized at 6 wk of age with both vaccines. Serum antibody levels were analyzed before (0) and 1, 2, 3, 4, 5, 12, and 21 wk postvaccination (wpv). The High lines displayed a significantly higher response than Low to both MG and PM. The difference in ymax between High and Low lines was 3.25-fold for PM response and 1.5-fold for MG response. Low lines had a significantly (P < 0.05) later tmax than High lines to MG, but not to PM. There was a significant (P < 0.05) positive correlation between the antibody responses to MG and PM, in High lines for the antibody ratios 0, 3, and 21 wpv and in Low lines for 0, 12, and 21 wpv. The ymax and tmax of antibody responses to the two vaccines were not correlated. The results on the kinetic differences of the antibody responses to MG and PM suggest that the kinetics and persistence of antibody reaction have different genetic regulation in response to each vaccine.

Antibody response to sheep red blood cells in major histocompatibility (B) complex aneuploid line of chickens

An integral part of the immune response is the production of antibodies specific for different antigenic challenges. Genes of the MHC encode products that regulate immunity. This study utilized the FCT-15 line of chickens, which is aneuploid for the chromosome containing the ribosomal RNA genes (rDNA) and the MHC or B complex to determine whether an antibody response to SRBC would vary as a function of B complex gene dose. Mating of trisomic parents (B15B15B15) animals produced progeny having either a disomic (B15B15), trisomic (B15B15B15), or tetrasomic (B15B15B15B15) B complex dosage. The number of B/rDNA chromosomes, and thus the B complex dosage was determined by feather pulp nucleolar typing of chicks at hatch. A 5% SRBC antigenic challenge, which induces a T cell-dependent antibody response, was injected at 6 wk of age. Samples taken prior to SRBC injection as well as 5, 8, and 12 d postinjection were assayed for total and mercaptoethanol-resistant antibody. Peak antibody titers (log2), day of peak titer and rate of titer decline were calculated using a quadratic equation for each bird. Differences among the three B complex dosages were evaluated by analysis of variance. Antibody titers rose from 5 to 8 d postinjection and declined thereafter without significant differences among the three B complex doses. Calculations from the quadratic equations showed that B complex dose affected neither peak antibody titer nor day of peak titer. However, trisomic and tetrasomic animals had significantly more rapid rates of decline from the maximum titer. In aneuploid chickens, changes in antigen processing, antigen presentation, or persistence of processed antigen may maintain levels of antibody production found in disomic chickens and explain the more rapid decline of titer.

Gordon Memorial Lecture. Stress, strains and resistance

1. Stress describes the bird's defence mechanisms and a stressor is the situation that elicits the defence response. 2. As the environment can be viewed as a composite of interacting stressors, the bird's success in coping with its environment depends on the severity of the stressors and the physiological ability to respond properly and thus maintain homeostasis. 3. The neural, endocrine and more recently immune systems are considered to be integrators of the stress response. Although stress responses may be necessary for survival in wild bird populations, they are often detrimental to efficient growth, skeletal integrity and disease resistance in domesticated fowl. 4. Stress responses are modified by the genetic components.

Major histocompatibility (B) complex-associated differences in the delayed wattle reaction to staphylococcal antigen

The influence of the major histocompatibility (B) complex on the delayed wattle reaction (DWR) to Staphylococcus aureus was studied in 109 segregants (B2/B2, B2/B5, and B5/B5) of a fourth generation cross between inbred Regional Poultry Research Laboratory lines 6(1) and 15(1). Chickens were sensitized at 6 weeks of age with S. aureus antigen. One week later, DWR was evaluated by injecting the right wattle with S. aureus antigen. Thickness measurements were taken 4, 24, 48, 72, and 96 hr after injection. A quadratic equation model was used for each bird to calculate maximum wattle thickness, hour of maximum response, and rate of response development and decline. In males, the maximum wattle thickness in response to S. aureus antigen was significantly greater in B2/B5 heterozygotes (1.77 +/- .07 mm) than in either homozygote, B2/B2 (1.36 +/- .13 mm) or B5/B5 (1.39 +/- .08 mm). Heterozygous males reached maximum response sooner and recovered more quickly than homozygous males but these differences were not statistically significant. In females, response developed later than in males but no B complex effect was detected in either rate of development or maximum response.

Hematology of Japanese quail selected for high or low serum corticosterone responses to complex stressors

Blood was collected from random-bred male Coturnix coturnix japonica and from quail selected genetically for high or low serum corticosterone responses to complex stressors after chronic exposure to short daily photoperiods and after exposure to long photoperiods. When compared to the low response quail, high response quail exhibited increased mean cellular hemoglobin values, reticulocyte numbers and heterophil percentages, and decreased monocyte and eosinophil numbers after exposure to long photoperiods. The data indicate that these corticosterone response lines can be partitioned by their hematological responses to photoperiodic manipulation.